PLEASE HELP, GREMLIN.

2000 Subaru Outback • 4WD Automatic • 100,000 miles

Car is acting like the throttle position sensor is bad ie: ****** acceleration at times, weird shifting, bad gas mileage, normally fixes itself when I turn off car and restart but will then do it after another 50-100 miles. I have replaced the TPS 4 times, along with the throttle body, oxygen sensor, air filter and had numerous resets. The check engine light will come on and turn itself off after a few trips. I have been told that the ECM is the only thing left to replace and that is a costly repair. Can this be a bad electronic control module?

First of all, if the check engine light comes on, then why are you reseting the light without pulling the code? Or have you pulled the code? If so, then what is the code?

Also, there are many more potential problems other than the ECM. Besides reading what the computer is trying to tell you, you need to check your ground cables from bat to engine/frame. As well as the wiring of your sensors/ECM/Transmission for burned insulation, corroded connectors or even something unplugged.

Thank you for your reply Ernest. The dealership has pulled the code every time before they reset it or nowadays my car will turn the check engine light off by itself. The code, according to them, is 75% TPS and 25% oxygen sensor, all of which I have repaired, sometimes twice. Kinda at a loss right now because it seems no one is willing to dupe it out far enough to find the genuine problem. Thank you though. Bryn

Most times a mechanic will pull a code and automatically assume it's the sensor that's the cause. A lot of times that's true. But a "True" technician will first test the wires/connectors for looseness, corrosion, dirt or damage. Also, it's necessary to make sure the sensor is being supplied the correct voltage by the computer and that all ground wires for your electrical system are good.

Becuse you've replaced the sensors with no change, I'd next suspect the wiring/connectors. If those are good, the circuits need to be checked to make sure the computer is sending the correct reference voltages and receiving the return signals it looks for from the sensors. If these are all good, I'd then suspect the computer.

Unfortunately, yes. Since the dealership in my area has stated the last thing they can do is change the computer, I've had to find a mechanic willing to go the extra mile. I believe I have one found, but since we've had bad weather I haven't been able to leave the car with him. As usual, it either starts flashing ATF light, check engine light somes on with no discernable reason. Or it has acceleration issues and then it happens. All of this leading up to hard shifting like my transmission is going south. Thank you fore asking though. Hopefully I can find someone with your expertise in my area.

Before doing this, find an experienced technician who has a capable scanner (up to date snap-on, genysis, mac or matco). They can conduct a drive test and attempt to duplicate your issues. When this happens, and while they're monitoring your system's sensors, they'll be able to take a snap-shot of what your system was doing at the time of the issue. Then they can compare this data to manufacturers specs.

This won't be cheap, but it will determine once and for all what your issue is. Only you can decide if your vehicle is worth spending the money. And keep in mind, as vehicles age, more problems arise. So even after you get this one issue fixed, expect another one sooner or later. Sometimes it makes more economical sense to just by a newer car.